package BinaryTree;

import com.sun.source.tree.Tree;

import java.util.Collection;
import java.util.Iterator;
import java.util.LinkedList;
import java.util.Queue;

/**
 * Created with IntelliJ IDEA.
 * Description:
 * User: 殇
 * Date: 2025-07-27
 * Time: 15:43
 */
public class BinaryTree {
    static class TreeNode {
        public char val;
        public TreeNode left;//左孩子的引用
        public TreeNode right;//右孩子的引用

        public TreeNode(char val) {
            this.val = val;
        }
    }


    /**
     * 创建一棵二叉树 返回这棵树的根节点
     *
     * @return
     */
    public TreeNode createTree() {
        TreeNode A = new TreeNode('A');
        TreeNode B = new TreeNode('B');
        TreeNode C = new TreeNode('C');
        TreeNode D = new TreeNode('D');
        TreeNode E = new TreeNode('E');
        TreeNode F = new TreeNode('F');
        TreeNode G = new TreeNode('G');
        TreeNode H = new TreeNode('H');

        A.left = B;
        A.right = C;
        B.left = D;
        B.right = E;
        C.left = F;
        C.right = G;
        E.right = H;

        return A;
    }

    // 前序遍历:中左右
    public void preOrder(TreeNode root) {
        if(root==null) return ;
        System.out.print(root.val+" ");
        preOrder(root.left);
        preOrder(root.right);
    }

    // 中序遍历
    void inOrder(TreeNode root) {
        if(root==null) return ;
        inOrder(root.left);
        System.out.print(root.val+" ");
        inOrder(root.right);
    }

    // 后序遍历
    void postOrder(TreeNode root) {
        if(root==null) return ;
        postOrder(root.left);
        postOrder(root.right);
        System.out.print(root.val+" ");
    }

    public static int nodeSize;


    //获取树中节点的个数：遍历思路
    void size(TreeNode root) {
        if(root==null) return ;
        nodeSize++;
        size(root.left);
        size(root.right);
    }

     //获取节点的个数：子问题的思路
    int size2(TreeNode root) {
        if(root==null) return 0;
        return size2(root.left)+size2(root.right)+1;
    }



    //获取叶子节点的个数：遍历思路
    public static int leafSize = 0;

    void getLeafNodeCount1(TreeNode root) {
        if(root==null) return ;
        if(root.left==null&&root.right==null){
            leafSize++;
            return ;
        }
        getLeafNodeCount1(root.left);
        getLeafNodeCount1(root.right);
    }

    //获取叶子节点的个数：子问题
    int getLeafNodeCount2(TreeNode root) {
        if(root==null) return 0;
        if(root.left==null&&root.right==null) return 1;
        int leftCount=getLeafNodeCount2(root.left);
        int rightCount=getLeafNodeCount2(root.right);
        return leftCount+rightCount;
    }

    //获取第K层节点的个数
    int getKLevelNodeCount(TreeNode root, int k) {
        if(root==null) return 0;
        if(k==1) return 1;
        return getKLevelNodeCount(root.left,k-1)+getKLevelNodeCount(root.right,k-1);
    }

     //获取二叉树的高度
     //时间复杂度：O(N)
    int getHeight(TreeNode root) {
        if(root==null) return 0;
        return 1+Math.max(getHeight(root.left),getHeight(root.right));
    }


    // 检测值为value的元素是否存在
    TreeNode find(TreeNode root, char val) {
        if(root==null) return null;
        if(root.val==val){
            return root;
        }
        TreeNode node1=find(root.left,val);
        if(node1!=null) return node1;
        TreeNode node2=find(root.right,val);
        if(node2!=null) return node2;
        return null;
    }

    //层序遍历
    public void levelOrder(TreeNode root) {
        if(root==null) return ;
        Queue<TreeNode> queue=new LinkedList<>();
        queue.add(root);
        while(!queue.isEmpty()){
            TreeNode cur=queue.peek();
            System.out.print(cur.val+" ");
            if(cur.left!=null)
                queue.offer(cur.left);
            if(cur.right!=null)
                queue.offer(cur.right);
            queue.poll();
        }
    }


    // 判断一棵树是不是完全二叉树
    boolean isCompleteTree(TreeNode root) {
        Queue<TreeNode> queue=new LinkedList<>();
        queue.add(root);
        boolean leaf=false;
        while(!queue.isEmpty()){
            TreeNode cur=queue.poll();
            if((cur.left==null&&cur.right!=null)||(leaf&&(cur.left!=null||cur.right!=null))){
                return false;
            }
            if(cur.left!=null){
                queue.add(cur.left);
            }
            if(cur.right!=null){
                queue.add(cur.right);
            }
            if(cur.left==null||cur.right==null){
                leaf=true;
            }
        }
        return true;
    }
}
